Field of the Disclosure
The present disclosure relates to a display device including a micro-lens film, and more particularly to a display device including a micro-lens film, which has a high fill-factor and a high luminance ratio and may prevent generation of moiré.
Discussion of the Related Art
Liquid crystal display devices display an image by regulating light transmittance of dielectric anisotropic liquid crystals using an electric field. A typical liquid crystal display device includes a liquid crystal display panel that consists of a thin film transistor substrate and a color filter substrate bonded to face each other, a backlight unit configured to emit light to the liquid crystal display panel, and a drive circuit configured to drive the liquid crystal display panel.
The aforementioned backlight unit includes a light source configured to generate light, a light guide panel configured to guide light so as to emit light to the liquid crystal display panel, a reflective sheet disposed below the light guide panel to reflect light to the liquid crystal display panel, and a micro-lens film for diffusion and concentration of light emitted from the light guide panel.
Here, the micro-lens film is classified into a fixed-shape micro-lens film and an unfixed-shape micro-lens film. In the case of the fixed-shape micro-lens film, as exemplarily shown in FIG. 1, lenses take the form of circular semi-spheres having the same size and are regularly arranged. The fixed-shape micro-lens film having a regular arrangement of lenses may achieve a high fill-factor and consequently a high luminance ratio, but cause generation of moiré as the regular arrangement of lenses overlaps the display panel, which results in deterioration of image quality and makes it difficult for the micro-lens film to be applied as an uppermost optical sheet.
In the case of the unfixed-shape micro-lens film, as exemplarily shown in FIG. 2, lenses take the form of oval semi-spheres other than circular semi-spheres having different sizes and are irregularly arranged. The unfixed-shape micro-lens film having an irregular arrangement of oval lenses may prevent generation of moiré. However, the irregular arrangement of lenses, as exemplarily shown in FIG. 2, may cause sparkles that are perceived as sparkling spots in large gaps, which results in deterioration of image quality as well as reduction of a luminance ratio due to a low fill-factor.
As described above, the fixed-shape micro-lens film causes generation of moiré, whereas the unfixed-shape micro-lens film causes generation of sparkling spots due to large gaps between lenses as well as a low luminance ratio due to a low fill-factor.